IDH1 and glioblastoma: Recognizing that survival was similar to patients with histologically classic glioblastoma IDH-wildtype WHO Grade 4, however, the cIMPACT update six recommends the diagnosis of “glioblastoma, IDH-wildtype, WHO Grade 4” for tumors with microvascular proliferation or necrosis or any of the molecular features of glioblastoma (TERT promoter mutation or EGFR gene amplification or +7/–10 chromosome changes).5 The 2021 WHO Classification further defined glioblastoma as exclusively IDH-wildtype.2